Time delay control

ABSTRACT

A time-delay control for applications such as operation of an internal combustion engine, where continued idle operation of the engine is desired after removal of the key from the usual controlling switch. A manually operated switch is connected between the load side of the controlled switch and a timed electrical relay for selectively energizing the relay while the engine is operating. The relay includes contacts in parallel with the manually operated switch and contacts in parallel with the controlled switch. The relay continues engine operation for a reset time, during which the key may be removed. At the conclusion of this period, the relay is de-energized and the engine is automatically shut down.

United States Patent Savage et a1.

[54] TIME DELAY CONTROL [72] Inventors: Paul E. Savage, c/o PO. Box 2422,

Pasco, Wash. 99302; Paul D. Sperline, 1208 Neel Loop, Kennewick, Wash. 99336 [22] Filed: June 8, 1970 [21] Appl.No.: 43,993

[ 51 3,680,539 1 Aug. 1, 1972 3,361,942 1/1968 Ojelid ..317/141 3,460,521 8/1969 Downing 123/102 3,508,242 3/1970 Kamberg ..317/141 3,510,671 5/1970 Stratton ..317/141 Primary Examiner-Laurence M. Goodridge Assistant ExaminerRonald B. Cox Attorney-Wells, St. John & Roberts [57] ABSTRACT 1 A time-delay control for applications such as operation of an internal combustion engine, where continued idle operation of the engine is desired after removal of the key from the usual controlling switch. A manually operated switch is connected between the 1 References Cited load side of the controlled switch and a timed electri- UNITED STATES PATENTS cal relay for selectively energizing the relay while the engine is operating. The relay includes contacts in 3,241,539 3/1966 Kuehn ..l23/198 a allel with the manually operated switch and con- McClain {acts in the controlled witch The relay Fraehon continues engine peration for a re-set time during 2,991,395 7/1961 Allen ..123/ 102 which the key may he removed At the conclusion f 3,049,649 8/1962 Burke ..317/141 this period the relay i de energized and the engine is 3,054,271 9/ 1962 McGrath ..317/ 141 automatically Shut down 3,148,830 9/1964 l-laskett ..317/141 3,308,903 3/1967 Sobel ..317/141 8 Claims, 3 Drawing Figures l l t /7 24 I I6 I 70 40/10 PATENTEDAUB 1 I972 3.680.539 sum 1 0F 2 I( I L 1 42 THERMAL DELAY sw/TcH 7 22 7'0 LOAD if 25 7 22 L /5 V I6 ELECTRON/C 3% ,T/MER 18 T0 LOAD P? UL D. SPER LINE ATTYS.

TIME DELAY CONTROL BACKGROUND OF THE INVENTION The apparatus described below is designed specifically to facilitate idling of diesel engines or other types of internal combustion engines wherein it is desirable to allow a few minutes of idle operation just before shut-down after normal engine operation under load. Such idle operation is normally required by diesel engine manufacturers to permit the internal temperature of the engine to stabilize before shutdown. Proper engine cooling increases engine efficiency and increases its normal life. It also reduces air pollution by minimizing the length of required engine operation prior to shut-down and by assisting in the improvement of engine maintenance and efficiency. The apparatus permits the operator of the engine to manually initiate the idle operation, remove the engine key or other control element and leave the engine running at idle. The device will then shut down the engine after a preselected period of time.

Various devices have previously been proposed for similar operation of engines. One example is shown in the McClain U.S. Pat. No. 2,861,558, which utilizes a mechanical timer wired in a rather complicated circuit with other electrical and mechanical devices for timing engine operation. It requires substantial modification of the normal engine control devices.

An electrical apparatus for the purpose of idling an engine is shown in the Kuehn U.S. Pat. No. 3,241,539. Again, the apparatus is relatively complicated and requires substantial modification of the normal control elements and circuitry for an engine. It is interposed between the battery and the engine circuits and any malfunction of the apparatus will result in malfunctioning of the engine. A protective shut-off device is also shown in the Newsom U.S. Pat. No. 3,174,468, which shows a pneumatic apparatus that is temperature controlled and which requires no electrical power.

Common practical obstacles to the use of all prior devices of this type are their complicated mechanisms and the difficulty of installation on various types and makes of engines. Each of the above devices would add considerably to the cost of the engine control circuits and mechanisms, and must be installed by modifying existing equipment or electrical circuits. The present apparatus uses electrical circuits which can be sealed for protection against damage due to the environment in which they are used or due to the vibration to which they are subjected. The sealed apparatus can be mounted as a unit on the control panel for the engine. The electrical connections for the apparatus require no disassembly or alteration of existing electrical connec tions in the engine control circuitry. Furthermore, the apparatus is manually operated and will not interrupt normal shut-down of the engine if the cooling period is not required or in the case of an emergency. After initiation of the apparatus by the operator, the engine may still be operated in its normal fashion without interruption or waiting for the pre-set time to expire. The device does not require power when not in operation.

SUMMARY OF THE INVENTION The present device is illustrated as used in combination with an internal combustion engine having an electrical control element, such as an electrical ignition system or solenoid operated fuel control valve mounted on the fuel pump. A key-operated switch is normally provided in such a system, the key being removed when the engine is inoperative. The present device comprises an electrical apparatus for selectively maintaining the engine in an operative condition following key removal. It comprises an electrically timed control having a relay with normally open contacts wired in parallel with the key-operated switch. A manually operated switch is connected in series between the controlled or load side of the key-operated switch and the timing circuit to initiate operation of the relay. After activating the manually operated switch, the key-operated switch can be shut off and the key removed during the cooling period. The relay also includes contacts wired in parallel with the manually operated switch to hold the relay in operation for the pre-set period controlled by the timing circuit. At the conclusion of the pre-set period, the relay is de-energized and the contacts are allowed to open, thereby terminating operation of the engine. The engine cannot be restarted or the relay reactivated without normal use of the key, providing theft protection and eliminating the need for constant attendance. If engine operation is required prior to the end of the period, normal use of the key-operated switch can be utilized in the usual fashion.

It is a first object of this invention to provide such a control apparatus which can be encased within a single housing and which can be readily installed on an engine control panel without modifying any existing engine control devices or circuitry.

Another object of the invention is to provide an electrical control for timing a terminal idle period prior to shut-down of an engine, which can be attached to the engine by simple electrical connections requiring no modification of existing wiring.

Another object of this invention is to provide such a control apparatus which can be adapted to any conventional type of engine control wiring or to other controlled devices requiring timed or intermittent automatic operation.

Another object of the invention is to provide such an apparatus which is selectively operable by the operator, so that the operator can choose to not use the timed operation if it is not required or desirable.

Another object of the invention is to provide such an apparatus which does not disturb normal operation of the engine, and which permits continued normal operation of the engine during the timed period by normal manual use of the engine controls.

These and further objects will be evident in the following disclosure, which describes two preferred forms of the invention. It is to be understood that various other alternatives also come within the scope of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic drawing of a first embodiment of the invention;

FIG. 2 is a schematic drawing of a second embodiment of the invention; and

FIG. 3 is a wiring diagram of the circuitry used in the second embodiment.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT The following discussion relates principally to a time delay control for idling an internal combustion engine, particularly a diesel engine, after removal of the usual key from the controlling switch in the engines electrical system. In the case of a diesel engine, the controlling electrical switch is either connected to the solenoid operated fuel control valve mounted on the fuel pump or to the solenoid engine cutoff mounted on the injector control rack. In the case of a gasoline engine, the key operated switch is interposed in the ignition system. In some instances, the controlling switch may not be key operated, but may be a control switch that is manually opened and closed. In some engine applications, the controlling switch might be interlocked with other devices that operate the switch in conjunction with other control functions such as a brake lever, transmission control or throttle. In addition, the timedelay control described herein is applicable to the control of other devices, motors and engines, since it is generally useful in sequentially operating a device by control of an electrical circuit. It may be used to either operate the device for a predetermined amount of time and then shut down the device, or can be used to operate a second similar time-delay control for intermittent operation of such a device in a repetitive fashion.

FIGS. 1, 2 and 3 illustrate schematically the application of the time-delay control to the electrical system for an internal combustion engine, specifically a diesel engine that must be idled for a short period of time before shut down. In the normal electrical control circuitry for such an engine, there is asource of electrical energy shown as battery 10, an electrical load such as the solenoid operated fuel control valve mounted on the fuel pump or solenoid engine cutoff mounted on the injector control rack and a power circuit connecting the source to the load. The power circuit includes a control switch, such as a key-operated switch 1 1. While switch 11 might have other terminals for accessories and starting functions, it essentially includes a pair of contacts leading to terminals 12, 13, these contacts being closed to complete a power circuit across terminals 12, 13 during normal operation of the engine and being opened when the engine is shut down. In other engines, the opening of switch 11 must be combined with other manually or automatically effected functions to properly shut down the engine. As will be described below, the present device can be applied to either type of engine circuitry.

As shown to the right in each of FIGS. 1, 2 and 3, the negative terminal of battery is grounded and its positive terminal is connected in the power circuit through switch 11 to a line 14 that leads from terminal 13 to the controlled electrical equipment or load (not shown). The present apparatus is connected in parallel with the existing circuitry and does not require any modification or revision of the wiring as designed and installed by the manufacturer of the equipment. The time delay control is shown to the left of switch 11, and can be housed within a single sealed enclosure (not shown) that can be mounted on an engine dashboard or other control panel.

FIG. 1 shows a first embodiment of the invention. It includes a relay 15 having a coil 16 and two sets of normally open relay contacts 17, 18. It also includes a thermal delay switch of conventional manufacture. This switch 20 is of the type that conducts current for a preselected period of time upon completion of a circuit through the switch, and then opens the circuit at the conclusion of the preselected period.

The contacts 17 are wired in a series circuit that includes the thermal delay switch 20 and coil 16 of relay 15. This circuit is in turn wired in parallel with the series circuit that includes battery 10 and switch 11. As shown, one side of contacts 17 is connected to terminal 13 on the load side of switch 11. The circuit through contacts 17, switch 20 and coil 16 is completed to ground.

The second set of normally opened contacts 18 is wired in parallel with switch 11 across terminals 12 and 13.

The time delay control is completed by a manually operated switch 21 which is open when the control apparatus is inoperative. Switch 21 is closed momentarily to initiate operation of switch 20 and coil 17. Switch 21 is wired in parallel with contacts 17. When used for engine shut down, switch 21 is preferably a conventional pushbutton switch that is momentarily closed upon being manually operated.

To provide a visual indication to an operator during operation of coil 16, a signal lamp 22 may be wired in parallel with coil 16. Lamp 22 will be lighted during the preselected period in which switch 20 maintains the coil 16 in operation.

During operation of the time delay control the contacts 17 act as a holding circuit for current to the time delay switch 20 and coil 16 controlled thereby. Contacts l8 serve to by-pass switch 11 during operation of the switch 20.

When used to automatically control the idle operation of an engine prior to shut down, the engine operator momentarily closes switch 21, thereby completing a power circuit through the key operated switch 11, switch 21, switch 20 and coil 16. The energizing of coil 16 in turn serves to close contacts 17 and 18, which respectively hold the power circuit to the switch 20 and by-pass switch 11. Switch 11 can then be opened such as by turning and removing the key.

The engine will continue to operate for the pre-set time governed by operation of thermal delay switch 20. At the conclusion of that period, the circuit through switch 20 will be opened, and coil 16 will release contacts l7 and 18, thereby opening the power circuit and shutting down the engine.

The entire operation requires no manual observation, and is entirely automatic. However, should it be desired to operate the engine prior to the conclusion of the time delay cycle, this can be accomplished by again closing switch 11, which will over-ride the operation of switch 20. The time delay control cannot be reactivated after the cooling period without use of the switch 11, providing needed theft protection. In addition, if it is essential that the engine be shut down without the idling period, as in the case of an emergency, this can be accomplished by operating switch 11 in the normal fashion, and not operating switch 21. Thus, the present arrangement provides maximum safety and flexibility to the operator of the engine, while adding to the normal operating capability an automatic cooling cycle for delayed engine operation prior to shut down.

FIGS. 2 and 3 illustrate a second embodiment of the invention using an electronic timer as a substitute for the thermal delay switch. The electronic timer has the advantage of being more accurate and reliable than the mechanically operative switch, and can be designed so as to be more independent of temperature changes. The elements common to the first embodiment are numbered identically in FIGS. 2 and 3. The timer circuit 23, shown in detail in FIG. 3, is connected to coil 16 by wire leads 24. The connection between contacts 17 and timer 23 includes a protective diode 25 to protect the sensitive components of timer 23 from accidential reversal of polarity. Timer 23 and lamp 22 are connected in parallel to ground, so that lamp 22 will be lighted during the preselected period of operation of timer 23 and coil 16.

As shown in FIG. 3, the actual wiring for the illustrated electronic timer 23 utilizes a third set of contacts 26 in relay 15. Contacts 26 are normally closed. The timer 23 is a two stage timer. Each stage is essentially identical. The first stage of the timer includesa capacitor 27 and resistor 28 in an R-C timing circuit connected to the gate of a field effect transistor 30. Transistor 30 and a zener diode 31 efiectively monitor the potential difference across capacitor 27. When the potential reaches a preselected value, transistor 30 conducts, thereby turning on transistor 32 and turning off transistor 33. The conducting transistor 33 up to this time has discharged capacitor 34 in the second R-C timing circuit, including resistor 35. Again, a field effect transistor 36 and zener diode 37 is used to monitor the charge on capacitor 34, eventually conducting to turn on transistor 38 and turn off a final controlling transistor 40. When transistor 40 is turned off, the circuit to coil 16 is opened. At this point, contacts 26 return to their normal closed condition, providing a grounded circuit across capacitor 27 and insuring that capacitor 27 is completely discharged at the beginning of the next timing cycle.

The electronic timer 23 illustrated in FIG. 3 requires no power when not in operation. There is therefore no continual wear on the electrical equipment. This circuit can also be selectively used or not used at the discretion of the operator, as discussed more fully above.

The circuitry shown in FIG. 3 can be readily adapted to electrical circuits having reversed polarity from that shown. To accomodate to such a reversal, one must simply reverse the two connections indicated in FIG. 3 by the numerals 41 and 42.

The particular application of this apparatus to diesel engines in trucks led to its development, but is not intended to be limiting as to the field of application of the invention. The time delay control has specific ad vantages with respect to diesel engines in trucks, since it permits the operator or driver to idle the engine, activate the time delay control by momentarily closing the switch 21, and then leave the engine unattended after opening the normal key operated switch 11. The operator can remove the key from switch 11 and lock the cab of the truck if he so desires. In addition, he is free to manually choose to shut down the engine without any such idling delay if this is desirable. He also is free to over-ride the time delay control and operate the engine in the usual fashion at any time. Furthermore, the installation of the present device requires no modification of existing wiring. It simply requires the connection of three wires, one to each side of switch 11 and one to ground. Should the present device fail for any reason, the normal power circuit for the controlled apparatus will not be affected in any manner.

The time delay control may be used to perform other functions necessary for completion of the timed operation. For instance, on some diesel engines, actual shutdown is accomplished by operation of an injector rack by activation of a solenoid. The control apparatus may be used to operate a second time delay control apparatus similar to that described above, in order that the required solenoid operation may take place for a pre-set time at the conclusion of the original preselected delay. The total sequence then includes three or more stages of timing circuits, not necessarily of equal time duration.

When used for intermittent operation of a device, two time delay controls are wired so that opening the circuit to the relay coil of the first initiates operation of the second, and opening of the circuit to the relay coil of the second initiates operation of the first. One time delay can be used to control the load circuit automatically, the other controlling a preselected delay while the load circuit is not activated.

Various modifications might be made in the choice of components in the apparatus and in the type of application to which it is directed. Therefore, only the following claims are intendedas definitions of the invention disclosed above.

Having thus described my invention, I claim:

1. In an apparatus for maintaining operation of the electrical power control circuit of an internal combustion engine for a preselected period of time, the combination with an internal combustion engine, an electrical power source, an electrical load device operable to shut down the engine and a power circuit connecting said source to said electrical load device; said power circuit including a control switch having a pair of contacts operatively connectedto the source and electrical load device respectively, the switch contacts being closed during normal operation of the power circuit and being open when the circuit is normally inoperative;

the improvement comprising:

electrical control means including first and second normally non-conductive circuits each adapted to be conductive upon energization of said electrical control means;

timing means operably connected to said electrical control means for selectively energizing said electrical control means for a pre-selected period of time;

said first normally non-conductive circuit being operably connected between the control switch contact connected to the load and said timing means for holding power to the timing during energization of said electrical control means;

said second normally non-conductive circuit being operably connected in parallel with the control switch for by-passing the control switch during energization of said electrical control means;

and selectively closeable switch means operably wired in parallel with said first normally non-conductive circuit.

2. The apparatus as set out in claim 1 wherein said I electrical control means comprises:

a relay having first and second pairs of normally open contacts within said first and second normally nonconductive circuits respectively, and a coil for controlling operation of said contacts.

3. The apparatus as set out in claim 2 wherein said timing means comprises a normally closed thermal delay switch wired in series with the relay coil.

4. The apparatus as set out in claim 2 wherein said timing means comprises an electronic timing circuit including a timed normally conductive circuit wired in series with said switch means and relay coil across the power source.

5. The apparatus as set out in claim 2 wherein said timing means comprises a normally closed thermal delay switch wired in series with the relay coil.

6. The apparatus as set out in claim 2 wherein said timing means comprises an electronic timing circuit including a timed normally conductive circuit wired in series with said switch means and relay coil across the power source.

7. In combination with an internal combustion engine having a source of electrical power;

a manually operable switch having one terminal connected to the source of power and its remaining terminal connected to a control circuit of the ens an apparatus for continuing normal operation of the engine control circuit afier the switch has been manually set so as to open the circuit between its terminals, comprising:

a relay having a coil and multiple contact points;

normally inactive electronic timing means operatively connected to said relay coil, said electronic timing means being selectivelyoperable to energize the coil for a pre-set period of time;

a first set of normally open contacts in said relay operably connectedin series between said remaining terminal of the ignition switch and said timing means;

a manually operable switch having normally open switch terminals wired in parallel with said first set of normally open contacts;

and a second set of normally open contacts in said relay operably connected across the terminals of said switch.

8. The apparatus as set out in claim 7, further comprising:

indicator means wired in parallel with said timing means for providing a sensory indication during activation of said timing means. 

1. In an apparatus for maintaining operation of the electrical power control circuit of an internal Combustion engine for a preselected period of time, the combination with an internal combustion engine, an electrical power source, an electrical load device operable to shut down the engine and a power circuit connecting said source to said electrical load device; said power circuit including a control switch having a pair of contacts operatively connected to the source and electrical load device respectively, the switch contacts being closed during normal operation of the power circuit and being open when the circuit is normally inoperative; the improvement comprising: electrical control means including first and second normally non-conductive circuits each adapted to be conductive upon energization of said electrical control means; timing means operably connected to said electrical control means for selectively energizing said electrical control means for a pre-selected period of time; said first normally non-conductive circuit being operably connected between the control switch contact connected to the load and said timing means for holding power to the timing during energization of said electrical control means; said second normally non-conductive circuit being operably connected in parallel with the control switch for by-passing the control switch during energization of said electrical control means; and selectively closeable switch means operably wired in parallel with said first normally non-conductive circuit.
 2. The apparatus as set out in claim 1 wherein said electrical control means comprises: a relay having first and second pairs of normally open contacts within said first and second normally non-conductive circuits respectively, and a coil for controlling operation of said contacts.
 3. The apparatus as set out in claim 2 wherein said timing means comprises a normally closed thermal delay switch wired in series with the relay coil.
 4. The apparatus as set out in claim 2 wherein said timing means comprises an electronic timing circuit including a timed normally conductive circuit wired in series with said switch means and relay coil across the power source.
 5. The apparatus as set out in claim 2 wherein said timing means comprises a normally closed thermal delay switch wired in series with the relay coil.
 6. The apparatus as set out in claim 2 wherein said timing means comprises an electronic timing circuit including a timed normally conductive circuit wired in series with said switch means and relay coil across the power source.
 7. In combination with an internal combustion engine having a source of electrical power; a manually operable switch having one terminal connected to the source of power and its remaining terminal connected to a control circuit of the engine; an apparatus for continuing normal operation of the engine control circuit after the switch has been manually set so as to open the circuit between its terminals, comprising: a relay having a coil and multiple contact points; normally inactive electronic timing means operatively connected to said relay coil, said electronic timing means being selectively operable to energize the coil for a pre-set period of time; a first set of normally open contacts in said relay operably connected in series between said remaining terminal of the ignition switch and said timing means; a manually operable switch having normally open switch terminals wired in parallel with said first set of normally open contacts; and a second set of normally open contacts in said relay operably connected across the terminals of said switch.
 8. The apparatus as set out in claim 7, further comprising: indicator means wired in parallel with said timing means for providing a sensory indication during activation of said timing means. 